syzbot has found a reproducer for the following issue on: HEAD commit: 97e36f4aa06f Revert "sched/core: kmsan: do not instrument .. git tree: https://github.com/google/kmsan.git master console output: https://syzkaller.appspot.com/x/log.txt?x=10e46944c80000 kernel config: https://syzkaller.appspot.com/x/.config?x=46c642641b9ef616 dashboard link: https://syzkaller.appspot.com/bug?extid=8ce7f8308d91e6b8bbe2 compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2 userspace arch: i386 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=143b8650c80000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15a22f2cc80000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/9931a9627dc6/disk-97e36f4a.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/1aafdb2fd6dc/vmlinux-97e36f4a.xz kernel image: https://storage.googleapis.com/syzbot-assets/90df5872c7ff/bzImage-97e36f4a.xz mounted in repro: https://storage.googleapis.com/syzbot-assets/ea75a01297dd/mount_0.gz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+8ce7f8308d91e6b8bbe2@xxxxxxxxxxxxxxxxxxxxxxxxx loop0: detected capacity change from 0 to 16 ===================================================== BUG: KMSAN: uninit-value in ondemand_readahead+0xddf/0x1720 mm/readahead.c:596 ondemand_readahead+0xddf/0x1720 mm/readahead.c:596 page_cache_sync_ra+0x72b/0x760 mm/readahead.c:709 page_cache_sync_readahead include/linux/pagemap.h:1210 [inline] cramfs_blkdev_read fs/cramfs/inode.c:217 [inline] cramfs_read+0x611/0x1280 fs/cramfs/inode.c:278 cramfs_lookup+0x1b8/0x870 fs/cramfs/inode.c:767 __lookup_slow+0x528/0x730 fs/namei.c:1685 lookup_slow+0x6a/0xc0 fs/namei.c:1702 walk_component fs/namei.c:1993 [inline] link_path_walk+0xe9a/0x1620 fs/namei.c:2320 path_openat+0x333/0x5750 fs/namei.c:3710 do_filp_open+0x24d/0x660 fs/namei.c:3741 do_sys_openat2+0x1f0/0x910 fs/open.c:1310 do_sys_open fs/open.c:1326 [inline] __do_compat_sys_openat fs/open.c:1386 [inline] __se_compat_sys_openat fs/open.c:1384 [inline] __ia32_compat_sys_openat+0x2ab/0x330 fs/open.c:1384 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] __do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178 do_fast_syscall_32+0x37/0x80 arch/x86/entry/common.c:203 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:246 entry_SYSENTER_compat_after_hwframe+0x70/0x82 Local variable ra.i created at: cramfs_blkdev_read fs/cramfs/inode.c:186 [inline] cramfs_read+0xc0/0x1280 fs/cramfs/inode.c:278 cramfs_lookup+0x1b8/0x870 fs/cramfs/inode.c:767 CPU: 1 PID: 5017 Comm: syz-executor948 Not tainted 6.2.0-syzkaller-81152-g97e36f4aa06f #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/16/2023 =====================================================
